DE102018112431A1 - Device protection when a ground connection loss event occurs - Google Patents

Abstract

A device has an electrical circuit configured to operate using a DC power supply voltage. The device also has a first ground terminal that is coupled to the electrical circuit and associated with the DC power supply. The device also has a second earth terminal. The device also has a capacitor coupled between the first ground terminal and the second ground terminal. The device may be configured to charge the capacitor from the electrical circuit upon a ground loss event at the first ground terminal.

Description

TECHNICAL AREA

Various examples of the invention relate to an apparatus and method for protecting electrical elements when a ground loss event occurs.

BACKGROUND

The 48 V power system application is receiving increasing attention in mild hybrid electric vehicles. A typical example of the 48 V power supply is a 48 V belt driven starter generator (Belt Driven Starter Generator - BSG). It is expected that more and more 48 V devices will be used in passenger cars, for example a 48 V e-Turbo, a 48 V compressor, 48 V electric power steering device, etc.

48 V devices typically have to communicate with 12 V devices, such as a vehicle bus system, for example as a controller area network (CAN), LIN, FlexRay etc. 48 V devices are therefore supplied from the 48 V power supply and have a transceiver to a low-voltage device, for example a 12/24 V device.

It has been observed that a ground connection loss event on a ground terminal associated with the 48 V power supply can cause damage due to over voltage and / or over current.

SUMMARY

There is therefore a need to provide protection against damage when a ground loss event occurs.

This need is met by the features of the independent claims. The features of the independent claims define embodiments.

One device has an electrical circuit. The electrical circuit is configured to operate using a supply voltage of a DC power supply. The device also has a first ground terminal that is coupled to the electrical circuit and associated with the DC power supply. The device also has a second earth terminal. The device also has a capacitor coupled between the first ground terminal and the second ground terminal.

A system has one device. The device has an electrical circuit. The electrical circuit is configured to operate using a supply voltage of a DC power supply. The device also has a first ground terminal that is coupled to the electrical circuit and associated with the DC power supply. The device also has a second earth terminal. The device also has a capacitor coupled between the first ground terminal and the second ground terminal. The system also has a first ground connection of the DC power supply, which is coupled to the first ground terminal. The system also has a second ground connection of a further DC power supply, which is different from the DC power supply. The second ground connection is coupled to the second ground terminal. The system also includes a DC / DC converter connected between the first ground connection and the second ground connection.

One method includes providing a supply voltage to an electrical circuit by direct current supply using a first ground terminal of the electrical circuit. The method also includes charging a capacitor from the electrical circuit coupled between the first ground terminal and a second ground terminal in response to a ground connection loss event at the first ground terminal.

One device has an electrical circuit. The device also includes a high voltage DC power ground terminal that is coupled to the electrical circuit. The device also has another DC power supply ground terminal. The device also has a capacitor coupled between the high voltage DC power ground terminal and the further DC power ground terminal.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the combinations specified in each case, but also in other combinations or on their own without departing from the scope of the present invention.

list of figures

• 1 schematically illustrates a system having a high voltage device and a low voltage device, according to various examples.
• 2 schematically illustrates a system having a high voltage device and a low voltage device, according to various examples.
• 3 illustrates an exemplary implementation of the high-voltage device according to various examples.
• 4 illustrates schematically a reference implementation of the system according to various examples.
• 5 illustrates schematically a reference implementation of the high-voltage device according to various examples.
• 6 illustrates schematically a reference implementation of the high-voltage device according to various examples.
• 7 schematically illustrates the system having a high voltage device and a low voltage device, according to various examples.
• The 8A and 8B schematically illustrate a temporal development of current-voltage characteristics of a capacitor, which is coupled between two ground terminals of the high-voltage device, according to various examples.
• 9 schematically illustrates a monitoring circuit and a limiting circuit associated with a capacitor, according to various examples.
• 10 illustrates schematically a temporal development of the voltage characteristics of the capacitor according to various examples, the voltage characteristics being controlled by the limiting circuit.
• 11 illustrates schematically a temporal development of the voltage characteristics of the capacitor according to various examples, the voltage characteristics being controlled by the limiting circuit.
• 12 schematically illustrates a monitoring circuit and a limiting circuit associated with a capacitor, according to various examples.
• 13 is a flowchart of a method according to various examples.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the invention will be described below in detail with reference to the drawings. It is clear that the following description of embodiments should not be interpreted as restrictive. It is not intended to limit the scope of the invention through the embodiments described below or the drawings, which are to be understood as illustrative only.

The drawings are to be regarded as schematic representations, and elements illustrated in the drawings are not necessarily drawn to scale. Instead, the various elements are shown in such a way that their function and their general purpose can be recognized by a person skilled in the art. Any connection or coupling between functional blocks, devices, components or other physical or functional units shown in the drawings or described herein can also be implemented by an indirect connection or coupling. A coupling between components can also be established via a wireless connection. Function blocks can be implemented in hardware, firmware, software or a combination of these.

Techniques are described below that facilitate protection of devices and electrical circuitry when a ground loss event occurs.

In the event of a ground connection loss event, a ground terminal associated with a DC power supply loses its connection to a ground connection of the DC power supply. Energy cannot be absorbed by the ground clamp during a ground loss event. The ground terminal may not be able to provide an electrical reference potential in the event of a ground loss event. There can be various reasons for such a ground loss event, and examples include loose plugs, low conductivity due to moisture, etc.

The techniques described herein can be used in a variety of scenarios. An exemplary scenario that can take advantage of the techniques described herein relates to a 48 V power supply, which is used in conjunction with a 12 V or 18 V or 24 V power supply (12 V - 48 V common Insert) is used. Such a scenario is typically observed in electric vehicles, for example mild hybrid electric vehicles. Thus, below, the main reference is made to such a 12 V - 48 V deployment scenario of a system that has both a 12 V power supply and a 48 V power supply. However, this is only to illustrate the techniques described, and these techniques can easily be applied to other scenarios, for example, in general, common use scenarios in which a low voltage power supply and a high voltage power supply are used. For example, as a basic rule in scenarios in which a first power supply and a second power supply are used together, it would be possible for one Supply voltage of a first battery of the first DC power supply is in the range from 20 V to 60 V, while supply voltage of a second battery of the second power supply is in a range of 6 V to 18 V. As a basic rule, the different DC power supplies can thus be configured to provide significantly different supply voltages.

In a 12 V - 48 V shared scenario, there may be a common ground for the 12 V power supply and the 48 V power supply. A DC / DC converter can be provided to couple the respective ground connections of the 12 V power supply and the 48 V power supply. Typically, it is not permitted that a direct connection between KL31 (low side / 0V of the 12 V battery) and KL41 (low side / 0 V of the 48 V battery) in 48 V devices without the DC / DC converter exists.

A 48 V device can be connected to the 48 V power supply or to both the 48 V power supply and the 12 V power supply, but the respective 0 V are not connected to the 48 V device , also if the ground connections of the 12 V power supply and the 48 V power supply are connected together to the DC / DC converter. If a 48 V device loses its mass (KL31 and / or KL41), this should not impair or destroy the 12 V devices.

In reference implementations (not illustrated in the figures), an isolation interface is used to connect any 12 V electrical circuit configured to operate using the 12 V power supply and a 48 V electrical circuit configured to operate using the 48 V power supply. For example, optical coupling can be used. Here, for example, disconnection of the electrical potentials, a 12V ground loss event or a 48V ground loss event will not interfere with the electrical devices. Less noise is also observed on respective ground connections. However, implementing the isolation interface for high speed signals and other signals can be costly.

An alternative scenario is based on a non-isolation interface. This non-isolation interface is typically less complex and expensive. With a non-isolation interface, there is no electrical isolation between 12 V circuits and a 48 V circuit. On the other hand, earth noise can be observed. 12V circuits can also be broken or destroyed if a 48V ground connection loss event is observed.

As a basic rule, in the various examples described herein, it is possible to use electrical circuits that are coupled through such a non-isolation interface. The various electrical circuits can be associated with different electrical devices or with a common electrical device. The various electrical circuits coupled via non-isolation interfaces can be configured to operate using different supply voltages, for example, a first electrical circuit can be configured to operate using a 48 V supply voltage while a second electrical circuit can be configured to operate using a 12 V supply voltage. For this purpose, a high-voltage power supply that has a respective battery that provides a high supply voltage, for example 48-V, and a low-voltage power supply that has a respective battery that provides a low supply voltage, for example 12-V, can be provided.

Techniques are described below that facilitate the avoidance of damage caused by a loss of ground event, even if non-isolation interfaces are used.

In one example, a device includes electrical circuitry configured to operate using a supply voltage from a DC power supply, such as a high voltage DC power supply, such as a 48 V DC power supply. The device also has a first ground terminal that is coupled to the electrical circuit and associated with the DC power supply. The device also has a second earth terminal. A capacitor is coupled between the first ground terminal and the second ground terminal.

For example, the second ground terminal may be associated with another DC power supply that is different from the DC power supply, for example, it would be possible for the second ground terminal to be associated with a low voltage DC power supply, such as a 12 V DC power supply, while the first ground terminal is associated with a high voltage DC power supply, such as a 48 V DC power supply. As an alternative example, it would also be possible for the second ground terminal to be associated with the same DC power supply as that with which the first ground terminal is associated.

Various effects can be achieved by providing the capacitor, which is coupled between the first ground terminal and the second ground terminal. First, protection of the electrical circuits can be provided because the capacitor can absorb energy from the electrical circuit upon a ground loss event at the first ground terminal. For example, the device may be configured to charge the capacitor from the electrical circuit upon the ground loss event. The energy absorbed by the capacitor does not cause damage to other circuits. Second, the capacitor may be able to detect the loss of ground event and possibly take appropriate measures to mitigate the effects of the loss of ground event. For example, it would be possible for monitoring circuits to be configured to monitor a voltage across the capacitor. Here, the voltage on the capacitor may indicate the ground connection loss event on the first ground terminal. A low (high) voltage across the capacitor may correspond to the absence (presence) of the ground loss event. A functionality of the electrical circuit can then be set as a function of the voltage on the capacitor. For example, if the electrical circuit includes an inverter interface for a motor / generator, as might be the case for a common BSG 12 V - 48 V deployment scenario, the device may be configured to include an inverter power circuit of the motor / Generator switches off depending on the monitoring of the voltage on the capacitor.

1 schematically illustrates a system 90 , The system has one device 100 and a device 150 on.

The device 100 has an electrical circuit 110 on. The electrical circuit 110 is configured to use a DC power supply voltage 171 , for example a 48 V DC power supply 171. The device 100 can thus be a high voltage device 100 or 48 V device. The device points to this 100 a high-side clamp 103 on that with the high-side / 48 V terminal of a 48 V battery 166 of the DC power supply 171 connected is. The device 100 also has a first ground terminal 101 on that with the electrical circuit 110 coupled and with the DC power supply 171 is associated. The earth clamp 101 is usually with a low-side / 0 V terminal on the battery 166 connected.

As in 1 illustrates the device 100 also another earth terminal 102 on. In the example of 1 is the earth clamp 102 with a DC power supply 172 associated by connecting to the ground connection 162 the DC power supply 172 that is configured to provide a supply voltage to the device 150 provide. However, it is an example implementation, and in other scenarios it would be possible for the ground terminal 102 with the DC power supply 171 is associated (see 2 ).

With further reference to 1 instructs the device 150 the electrical circuit 155 configured to use the supply voltage of the DC power supply 172 to function, for example a low-voltage DC power supply, such as a 12 V DC power supply. The device 150 can therefore be called a low voltage device or 12 V device. The device 150 has a high-side clamp 152 on that with a 12v battery terminal 167 the DC power supply 172 connected and connected to the circuit 155 is coupled. The device 150 also has a ground terminal 151 on that with the electrical circuit 155 coupled and with the DC power supply 172 is associated. The earth clamp 151 is therefore with a 0 V terminal of the battery 167 connected.

As in 1 are illustrated, the electrical circuit 110 and the electrical circuit 155 via a non-isolation interface 156 of the system 90 coupled.

Specifically, the circuit shows 110 a low voltage part 111 and a high voltage part 112 on. The low voltage part 111 is over the non-isolation interface 156 with the electrical circuit 155 coupled.

In 1 are a ground connection 162 the DC power supply 172 of the system 90 as well as a ground connection 161 the DC power supply 171 of the system 90 illustrated. The ground connections 161 . 162 are connected to each other via a DC / DC converter 165 coupled.

In 1 is a ground connection 168 which illustrates the ground terminal 101 of the device 100 that with the DC power supply 171 is associated with the battery 166 combines. In the event of a ground connection loss event at the ground terminal 101 the connection goes 168 lost. The connection 168 can break physically or become non-conductive, etc.

Damage to the electrical circuit, for example 155 and / or the low voltage part 111 the electrical circuit 110 to avoid is a capacitor 120 between the earth terminal 101 and the earth clamp 102 of the device 100 coupled.

3 illustrates details regarding the device 100 , The device 100 has the low voltage part 111 and the high voltage part 112 on that via a DC / DC converter 210 are coupled. Low Dropout Regulators (LDOs) 211 . 212 are in the low voltage part 111 provided. The LDO is with a transceiver 213 associated via the non-isolation interface 156 with the electrical circuit 155 of the device 150 (in 3 not illustrated) is connected. The non-isolation interface could, for example, be implemented via a vehicle bus system, such as a CAN bus or the like. The transceiver 213 can be configured to control signals through the non-isolation interface 156 to receive and / or transmit.

The LDO 212 is with a control unit 214 associated. The control unit 214 sets gate drivers for power switches 216 of the high voltage part 112 um what is sometimes called performance level. The power switch 216 and a capacitor 215 put a converter for the motor / generator 220 around.

Next is the function of the capacitor 120 under reference implementations of the device 100 ' that in the 4 to 6 is illustrated as a yardstick.

The 4 to 6 illustrate aspects relating to a reference implementation of the device 100 ' , As you can see, the reference implementation of the device shows 100 ' the earth clamp 102 and the capacitor 120 compared to the device 100 of the 1 to 3 not on.

During normal operation (no ground loss event), current flows from the 48 V battery 166 into the device 100 ' over the clamp 103 , then flows through the circuits in the device 100 ' , including the power level 112 , the power supply part and control part 111 , and then flows out of the device 100 ' via the 48 V earth terminal 101 to the inverter. The current eventually flows to the negative pole of the battery 166 over the ground connections 168 . 161 back. The transceiver 213 is supplied by a 5 V supply voltage, which is supplied by the DC / DC converter 210 and the LDO 211 is produced. In normal operation, the electrical potential is that of the non-isolation interface 156 loaded, 5 V DC, the path of electrical potential from an output signal of the device 100 starts and through the electrical circuit 155 . 12-V -Masseklemme 151 connected to the body of a vehicle, for example, ground connection 162 , DC / DC converter 165 and finally back to the negative pole of the battery 166 because the DC voltage is derived from the 48 V battery. All of this also applies to the implementation of the device 100 according to the 1 to 3 ,

As a basic rule, if the ground connection 168 in the event of a ground loss event, all of the working currents find a different path to the negative pole of the battery 166 to return. When implementing the reference of the device 100 ' without the earth clamp 102 , there is only one output through which the working current goes to the negative pole of the battery 166 can go back. The output is the output port of the transceiver 213 via the non-isolation interface 156 , With reference to 4 If 48 V electrical potential flows to point A via terminal KL40 of the inverter, then the 48 V potential flows in all possible paths to point B, which is the output port of the transceiver 213 is. After reaching point B, the potential of point B loads the electrical components of the transceiver 213 ,

Two main paths from point A to point B are in the 5 and 6 for the reference implementation of the device 100 ' illustrated.

After the ground connection 168 the power supplies for the motor / generator operate in the event of a ground connection loss event 220 normal during a given period because of energy present in the capacitor 215 is stored, provides a current. The length of the given period depends on the working current of the inverter, which is about 100 mA if the power level 112 not working. In general, the capacitance of the capacitor is sufficient 215 up to several 1000 microfarads. Then for an assumed capacitance of the capacitor 215 from 5 mF the length of the given period 2 to 4 seconds.

V_{_GND_48v_KL41} / V_S1 ist Spannung von der Masseklemme 101 zu dem Masseanschluss 161. V_{_c_dclink} ist die Spannung an dem Kondensator 215. VCC ist die Versorgungsspannung.For example, it may take 2 seconds for the voltage across the capacitor 215 is reduced from 60 V (maximum value of 48 V) to 20 V (minimum value of 48 V). This means that all power supplies will function normally during the 2 second period. In other words, the DC power supply also normally produces 5 V. The path from point A to point B, which in 5 is the 5 V generation path. Regarding the voltage V_vcc_kl41 from VCC to the negative pole of the 48 V battery 166: $$\begin{array}{l}{\text{V}}_{\text{\_}}{{}_{\text{VCC}}}_{\_}{}_{\text{KL41}}=\text{VCC}+{\text{V}}_{\_\text{GND\_48V\_KL41}};\\ {\text{V}}_{\text{\_}}{{}_{\text{GND}}}_{\_48\text{V\_}}{}_{\text{KL41}}:={\text{V}}_{\_\text{S1}}={\text{V}}_{\_48\text{V\_battery}}-{\text{V}}_{\text{\_c\_dclink}},\end{array}$$

V _{_GND_48v_KL41} / V_S1 is voltage from the ground terminal 101 to the ground connection 161 , V _{_c_dclink} is the voltage across the capacitor 215 , VCC is the supply voltage.

It is observed that the voltage V_s1 increases as the voltage _{V_c_dclink is} reduced. V_s1 is 40 V when V _{_c_dclink is} 20 V. Therefore, the voltage V_vcc_kl41 is 45 V, which is more than the maximum surge voltage of 40 V, which is the output port of the transceiver 213 withstands, and the voltage V_vcc_kl41 rises above 45 V after the time of 2 s. Finally, the voltage V_vcc_kl41 can reach 60 V. The output port of the transceiver 213 is destroyed during the stage of V_vcc_kl41 between 40 V and 60 V.

A scenario where the working current is the maximum current of the power stage 112 at the moment of the ground loss event is considered. In general, it is about 250 A for a common BSG 12 V 48 V application scenario. The length of the period of time for V_s1 to rise from 60 V to 20 V is approximately 1 ms. That means the output port of the transceiver 213 if the device is destroyed within several ms after the ground connection loss event 100 works with a maximum high current of 250 A.

If you consider that the power level 112 with high current at the moment of the ground connection loss event at the ground terminal 101 works, the working current tries, among other things, through the path between A and B, as in 6 illustrated to flow. This is because there can be many paths between points A and B that are not analyzed here.

The analysis above for the paths between points A and B proves that the potential of the transceiver 213 can destroy, depends on the voltage V_s1.

Techniques are described below that allow the voltage V_s1 to be adapted and / or monitored to measure. According to various examples, this is done by providing the capacitor 120 and the further earth terminal 102 (please refer 1 to 3 ) in the device 100 achieved.

The earth clamp 102 provides an alternative backup route for current flow back to the battery 166 ready, even in the event of a ground connection loss event at the ground terminal 101 , The current therefore does not need to go through the transceiver 213 to flow. This helps prevent damage to the transceiver 213 to avoid.

As a basic rule, there are various options for converting the earth terminal 102 are conceivable. The condenser 120 can, for example, between the 48 V ground terminal 101 and the housing of the device 100 be connected in series. The housing can be implemented by a metal housing. The housing can therefore be the earth terminal 102 implement.

Typically the ground connection 162 implemented between electrical circuits in a passenger car by wires and the vehicle metal body.

Details regarding the capacitor 120 and the earth clamp 102 are also in 7 illustrated.

7 illustrates aspects related to the device 100 , The example of 7 generally corresponds to the example of 1 ,

In addition, in 7 several leakage inductors 251 to 255 shown. The leakage inductor 255 L_stray_BSG_48VBat + is the inductor of the wire between the device 100 and the 48 V battery 166 , The leakage inductor 254 L_stray_BSGcase_CarBody is the inductor of the ground connection 169 between the earth terminal 102 and the ground connection 162 the negative pole of the 12 V battery 167 the power supply 172 , The leakage inductor 251 L_stray_CarBody_DCDC is the inductor of the connection between the negative pole of the 12 V battery 167 and the DC / DC converter 165 , The leakage inductor L_stray_DCDC_48VBat 252 is the inductor of the wire that connects the ground 161 between the DC / DC converter 165 and the negative pole of the 48 V battery 166 implements.

Next are typical values for the inductances of the inductors 251 to 255 given: A typical inductance of the inductor 255 For example, L_stray_BSG_48VBat + would be 2 µH. Between the earth clamp 102 and the negative pole of the 12 V battery 167 there may be very little resistance like the leakage inductor 254 L_stray_ BSGcase_CarBody: in an exemplary implementation, the inductance between the ground metal contact of the front metal body and the ground metal contact of the rear metal body is slightly more than the leakage inductor 252 L_stray_CarBody_DCDC. The inductance of the leakage inductor 252 L_stray_DCDC_48VBat- can be about 0.3 µH. The inductor L_stray_BSGcase_48VBat- is 3 as the sum of the 3 leakage inductors 254 . 251 . 252 defined in series, including L_stray_ BSGcase_CarBody, L_stray_CarBody_DCDC and L_stray_DCDC_48VBat-. The combined inductor L_stray_BSGcase_48VBat- is assumed to be 0.5 µH for the following circuit simulation.

A respective simulation circuit that uses such values for the inductances is shown in 8A and 8B illustrated.

VS1 provides the 48 V battery 166 L1 represents the inductor L_stray_BSG_48VBat + with an initial current of 250 A. C3 represents the capacitor 215 with 60 V initial voltage. R1 represents a simplified equivalent circuit of the motor / generator. C1 represents the capacitor 120 L2 represents the combined inductor L_stray_BSGcase_48VBat-. AM1 tests the current that flows through C1. VM2 tests the voltage from the earth terminal 101 to the negative pole of the 48 V battery 166 , The voltage from VM2 in 8th is tested, establishes the voltage between the ground terminal 101 and the negative pole of the 48 V battery 166 represents.

VM2 thus corresponds to V_S1. As can be seen, there is also a strong correlation between VM2 and V_C, which is the voltage across the capacitor 120 is.

To simplify the simulation circuit, the inverter bridge was used by the switches 216 and the engine 220 is implemented, roughly equated to a resistance R1 of 0.19 ohms for transient simulation. The 0.19 ohm resistor simulates a load absorption current of 250A with a terminal voltage of 48 V (0.19 = 48/250).

The simulation results are also for a capacitance of the capacitor of C = 1 µF in 8A shown and in 8B for a capacitance of the capacitor of C = 1000 µF.

The following observations can be made based on the simulation results. First, by increasing the capacitance of the capacitor 120 a trend that the voltage VM2 rises slowly and evenly to 60 V and the start voltage (at time 0) changes to smaller values. Second, if the voltage waveform is divided into three sections containing the start voltage part, the resonance part and the steadily rising part, the frequency of the resonance part changes to lower values by the capacitance of the capacitor 120 is increased.

It follows from the 8A and 8B that in general there may be a trend towards larger capacitance for the capacitor 120 preferable. This is to avoid sudden increases in the voltage across the capacitor 120 and to reduce the frequency of the resonance from the capacitor 120 is formed. As a basic rule, the capacitance of the capacitor 120 not less than 10 µF, optionally not less than 100 µF, furthermore optionally not less than 1000 µF.

As a note, it was observed that breaking the ground connection 168 requires a certain amount of time in the event of a loss of ground connection. The time span can be modeled, for example, by an erase time of a relay. Typical time spans are in the range of 100 to 500 microseconds. The short time spans in the 8A and 8B , namely a simulation showing the break time of the ground connection 168 not taken into account, are illustrated, can be ignored.

In summary, it is possible to obtain a relatively evenly increasing voltage from VM2 if the capacitor has suitable capacitance 120 according to the specific circuit parameter of the device 100 is selected.

You have to understand that the 8A and 8B represent an example that the damage protection functionality of the capacitor 120 motivated. Nevertheless, they approximate 8A and 8B the functionality. For example, in the 8A and 8B takes into account the voltage VM2, which is the voltage between the ground terminal 101 and the negative pole of the battery 166 modeled. An even better approximation would be the voltage between the earth clamp 101 and the ground connection 162 because it's the exact voltage that the transceiver 213 loaded, without voltage on the inductor 152 L_stray_CarBody_DCDC and the inductor 252 L_stray_DCDC_48VBat-. As mentioned above, the inductance of the leakage inductor is L_stray_BSGcase_CarBody 254 very low, especially when compared to the inductance of the combined inductors 251 . 252 , Therefore, the simulation presented above is a worst case scenario with an additional margin due to the low inductance of the inductor 254 ,

The techniques described above help prevent damage to electrical components such as the transceiver 213 by means of the capacitor 120 submissions. In addition to such damage protection functionality, the capacitor can 120 also provide additional functionality, such as monitoring functionality, which helps to detect the loss of ground connection events. That will be discussed in more detail with reference to 9 discussed.

9 illustrates aspects related to a monitoring circuit 401 and a limiting circuit 450 , The limiting circuit 450 can be by any type of electrical device or a combination of several Types of electrical devices, such as a metal oxide field effect transistor, bipolar transistor with insulated gate electrode, transistor and immediately implemented. The monitoring circuit 401 can be implemented immediately using a separate device or an integrated chip.

As in 9 is illustrated, the monitoring circuit with the capacitor 120 connected in parallel. The limiting circuit is in the same way 450 with the capacitor 120 connected in parallel. In some examples it is possible to use either the monitoring circuit 401 or the limiting circuit 450 provide. It is not necessary in all scenarios that both the monitoring circuit 401 as well as the limiting circuit 450 provided.

The monitoring circuit 401 is configured to a voltage 489 on the capacitor 120 to monitor. The monitoring circuit 401 can be configured to a control signal 431 issue. The control signal 431 may indicate a ground connection loss event at the ground terminal 101 Clues. This is due to the fact that there is a correlation between the voltage 489 on the capacitor 120 and the ground connection loss event at the ground terminal 101 , as above for example with reference to the 8A and 8B explains, exists.

The control signal 431 can for example from the control unit 214 be received. Then the motor / generator 220 be switched off by the inverter depending on the monitoring of the voltage 489 on the capacitor 120 is controlled, for example, taking into account the control signal 431 , For example, it would be possible to turn off the inverter power switches if the voltage 489 on the capacitor exceeds a threshold. Then a power current can be switched off when the motor / generator 220 works in monitoring mode. This helps the discharge time of the capacitor 215 to expand. However, there is more time to take a protective action after the loss of ground connection.

The limiting circuit 450 is configured to the voltage 489 on the capacitor 120 to monitor. For example, the limiting circuit 450 be configured to the voltage 489 limit, which effectively creates an electrical short circuit between the earth terminals 101 . 102 is created. The limiting circuit 450 can the tension 489 control to stay below a threshold and / or to stay in a belt-shaped area. Operation of the limiting circuit 450 can be set on request.

By means of the limiting circuit 450 Various effects can be achieved: it is possible to absorb energy in the leakage inductors 251 to 255 is saved in the event of a loss of ground connection. It is possible to have a free-running current path for the leakage inductors 251 to 255 to provide in the event of a loss of ground connection. The ground offset voltage can be smoothed. The rate of rise of the mass offset voltage can be slowed down.

Next is the function of the circuits 401 . 450 in connection with the 10 and 11 illustrated.

The 10 and 11 illustrate the voltage V_C across the capacitor 120 depending on the time.

In normal operation (no ground loss event), power current flows through the power stage 112 and flows out of the device 100 via the earth clamp 101 and flows to the negative pole of the 48 V battery 166 on the leakage inductor 253 L_stray_48VECU_48VBat- back. There is no loss of ground connection event.

Next, at t0, there is a ground connection loss event at the ground terminal 101 on. The ground connection 168 breaks.

Then the power current and the control current flow to the metal case which is the ground terminal 102 implements on the capacitor 120 and flow to the negative pole of the 48 V battery 166 via the leakage inductors 254 . 251 . 252 and the DC / DC converter 165 back.

If the tension 489 the threshold voltage 481 reached at t1, the monitoring circuit gives 401 the respective status signal 431 to the control unit 214 out; then the control unit switches 214 the power level 112 and therefore the motor / generator 220 out.

Optionally, the control unit draws 214 the 48 V ground loss event in the ROM by checking the ground_loss_flag and feedback of the ground loss fault over the communication bus 156 established.

The switches 216 the performance level 112 are completely switched off at t2. The power current is switched off. Then the tension rises 489 slow due to the persistent control current of the device 100 and free-running current of the leakage inductors 251 to 255 further. The condenser 120 is about the capacitor 215 loaded.

If the tension 489 the voltage threshold 482 reached at t3, controls the limiting circuit 450 the voltage 489 by performing one of two optional actions. action 1 , in the 10 is shown to keep the tension in a belt-shaped area, the upper limit tension 482 is less than the maximum surge voltage of the transceiver 213 , Action 2, which in 11 Shown is a bypass path for short-circuiting the capacitor 120 and provide for short-circuiting.

From the 9 and 10 it can therefore be seen that it is generally possible for the limiting circuit 450 is configured to the voltage 489 to control so that they are below the threshold 482 remains, and is optionally configured to the voltage 489 to control above the threshold 483 to stay. The limiting circuit 450 is therefore configured to a low impedance bypass path of the capacitor 120 to build.

The control unit 214 receives the motor / generator 220 deactivated as long as the ground_loss_flag is set. Other parts of the device 100 how the transceiver 213 , can function normally. That means internal circuits of the device 100 with the exception of the power level 112 can function normally after the ground loss event.

As can be seen, the voltage load on the transceiver is after the ground loss event 213 less than the maximum surge voltage if the voltage thresholds 481 to 483 have been set appropriately.

This can involve measuring that there is enough time from t0 to t1 to avoid noise interference near time t0, which is the moment of the ground loss event.

It should also be ensured that there is enough time from t1 to t3 to ensure that the switches 216 the performance level 112 switched off completely before limiting.

Also the sum of the tension should 482 and the supply voltage for the transceiver 213 be less than the maximum transceiver surge voltage 213 sufficient margin is required. In 10 For example, it is shown that the threshold for 181 is 10 V and the threshold 482 25 V. The maximum surge voltage of the transceiver is 40 V, and the voltage of the supply power VCC of the chip is 5 V. The sum of 30 V (25 + 5 = 30) is therefore less than 40 V with a margin of 10 V.

As a basic rule, the monitoring circuit 401 and the limiting circuit 450 can be implemented in various ways. An exemplary implementation is in 12 illustrated.

12 illustrates aspects related to the limiter circuit 450 and the monitoring circuit 401 ,

In 12 becomes the capacitor 120 loaded in response to a ground loss event. If the tension 489 10 V is reached, the transistor switches 415 the current flows from the supply V3V3 to the earth terminal 102 via the zener diode 412 , the resistance 413 and the transistor 415 a because the supply voltage V3V3 with respect to the voltage at the ground terminal 102 Is 13.3 V (3.3 plus 10 V). Before the ground connection loss event is the voltage level of the output signal 431 the high level (3.3 V) with regard to the voltage at the ground terminal 101 , The voltage of the output signal 431 changes to the low level (about 0 V to the voltage at the ground terminal 101 ) after the transistor 415 was switched on. The control unit 214 thus switches the power level 112 off after the input change of the control signal 431 was recorded. Then the capacitor 120 continues to be slowly charged by the control current. If the tension 489 of the capacitor 120 When the voltage reaches 20 V, the gate capacitor of the switch begins 463 to be loaded. The desk 463 turns on completely when the voltage 489 25 V is reached, provided that the threshold voltage of the gate of the switch 463 Is 5 V. After turning on the switch 463 , the capacitor starts 120 to discharge yourself quickly. If the tension 489 falls to about 20 V, the switch switches 463 out again. And then the switching on and off are repeated, finally the damping voltage is in a belt-shaped range from about 20 V to about 25 V (see 10 ) limited.

13 10 is a flowchart of an example method according to various examples.

At block 1001 a ground loss event may or may not occur. A ground connection loss event may correspond to the loss of an electrical ground connection at a respective ground terminal that provides ground functionality for an electrical circuit of a device. The ground terminal can be associated with the DC power supply.

Then if a loss of ground event at block 1001 occurs, a capacitor at block 1002 loaded. The capacitor is between the first ground terminal at which the ground loss event at block 1001 occurs, and the second ground terminal coupled. The second ground terminal may be associated with the same DC power supply that the first ground terminal is associated with, or may be associated with a different DC power supply (see 1 and 2 ).

With the optional block 1003 a voltage across the capacitor is monitored. A monitoring circuit can be used for this (see 9 ). By monitoring the voltage across the capacitor, the ground connection loss event can be detected. Appropriate countermeasures can then be taken, for example, by outputting a control signal that controls the operation of the circuit for which the first ground terminal at which the ground loss event occurs provides ground functionality.

The following can be done with an optional block 1004 the voltage across the capacitor can be limited. For example, the voltage may be limited to below an upper threshold (see 10 and 11 ), and optionally above a lower threshold (see 11 ) to stay.

In summary, techniques have been described above in which a capacitor is provided between a first ground terminal and a second ground terminal. For example, the first ground terminal may be a 48 V ground terminal of a 48 V DC power supply. The second earth terminal can be implemented by the metal housing of the respective device. Typically, the metal housing is connected to a 12 V ground connection via a 12 V DC power supply.

Techniques have been described that facilitate smoothing the voltage between the first ground terminal and the second ground terminal during a loss of ground event. Techniques for detecting the loss of ground connection event are described, for example, by monitoring a voltage across the capacitor. Techniques have also been described that facilitate limiting the voltage across the capacitor to protect against overvoltage / overcurrent of sensitive circuits.

In particular, the following examples have been described.

• eine elektrische Schaltung, die konfiguriert ist, um unter Verwenden einer Versorgungsspannung einer Gleichstromversorgung zu arbeiten,
• eine erste Masseklemme, die mit der elektrischen Schaltung gekoppelt und mit der Gleichstromversorgung assoziiert ist,
• eine zweite Masseklemme, und
• einen Kondensator, der zwischen der ersten Masseklemme und der zweiten Masseklemme gekoppelt ist.

Example 1. Device that includes:

• an electrical circuit configured to operate using a supply voltage of a DC power supply,
• a first ground terminal coupled to the electrical circuit and associated with the DC power supply,
• a second earth terminal, and
• a capacitor coupled between the first ground terminal and the second ground terminal.

Example 2. Device according to example 1,
wherein the second ground terminal is associated with another DC power supply that is different from the DC power supply.

Example 3. Device according to example 1 or 2,
the device configured to charge the capacitor from the electrical circuit upon a ground loss event at the first ground terminal.

Example 4. Device according to example 3,
wherein the device is configured to charge the capacitor through another capacitor of the electrical circuit.

• eine Überwachungsschaltung, die konfiguriert ist, um eine Spannung an dem Kondensator zu überwachen.

Example 5. Apparatus according to any of the preceding examples, further comprising:

• a monitoring circuit configured to monitor a voltage across the capacitor.

Example 6. Device according to Example 5,
the electrical circuit comprising an inverter for a motor / generator,
wherein the device is configured to turn off the motor / generator by controlling the inverter in response to monitoring the voltage on the capacitor.

Example 7. Device according to Example 6,
wherein the device is configured to turn off switches of the inverter if the voltage across the capacitor exceeds a first threshold.

• eine Begrenzungsschaltung, die konfiguriert ist, um eine Spannung an dem Kondensator zu steuern.

Example 8. The device of any of the preceding examples, further comprising:

• a limiting circuit configured to control a voltage across the capacitor.

Example 9. Device according to Examples 7 and 8,
wherein the limiting circuit is configured to control the voltage across the capacitor that it remains below a second threshold that is greater than the first threshold.

Example 10. Device according to Example 8 or 9,
wherein the clipping voltage is configured to control the voltage across the capacitor to remain above a third threshold.

Example 11. Device according to one of Examples 8 to 10,
wherein the limiting circuit is configured to form a low-resistance bypass path of the capacitor.

Example 12. Device according to one of the preceding examples,
wherein the electrical circuit comprises an inverter for a motor / generator and further comprises a transceiver for a vehicle communication bus system.

Example 13. Device according to one of the preceding examples,
wherein the capacitance of the capacitor is not less than 10 µF, optionally not less than 100 µF, further optionally not less than 1000 µF.

• ein Metallgehäuse, das die zweite Masseklemme umsetzt.

Example 14. The device of any of the preceding examples, further comprising:

• a metal housing that implements the second earth terminal.

• das Gerät nach einem der vorstehenden Beispiele,
• einen ersten Masseanschluss der Gleichstromversorgung, der mit der ersten Masseklemme gekoppelt ist.
• einen zweiten Masseanschluss einer weiteren Gleichstromversorgung, die von der Gleichstromversorgung unterschiedlich ist, wobei der zweite Masseanschluss mit der zweiten Masseklemme gekoppelt ist, und
• einen Gleichstrom-/Gleichstromwandler, der zwischen dem ersten Masseanschluss und dem zweiten Masseanschluss verbunden ist.

Example 15. System that includes:

• the device according to one of the preceding examples,
• a first ground connection of the DC power supply, which is coupled to the first ground terminal.
• a second ground connection of a further direct current supply, which is different from the direct current supply, the second ground connection being coupled to the second ground terminal, and
• a DC / DC converter connected between the first ground terminal and the second ground terminal.

• eine weitere elektrische Schaltung, die konfiguriert ist, um unter Verwenden der zweiten Versorgungsspannung zu arbeiten,
• wobei die elektrische Schaltung und die weitere elektrische Schaltung über eine Nicht-Isolation-Schnittstelle gekoppelt sind.

Example 16. The system of Example 15, further comprising:

• another electrical circuit configured to operate using the second supply voltage,
• wherein the electrical circuit and the further electrical circuit are coupled via a non-isolation interface.

• eine erste Batterie der Gleichstromversorgung,
• eine zweite Batterie der weiteren Gleichstromversorgung,
• wobei eine Low-Side-Klemme der ersten Batterie mit dem ersten Masseanschluss gekoppelt ist, und
• wobei eine Low-Side-Klemme der zweiten Batterie mit dem zweiten Masseanschluss gekoppelt ist.

Example 17. The system of Example 15 or 16, further comprising:

• a first battery of the DC power supply,
• a second battery for the further direct current supply,
• wherein a low-side terminal of the first battery is coupled to the first ground connection, and
• wherein a low-side terminal of the second battery is coupled to the second ground connection.

Example 18. System according to Example 17,
wherein a supply voltage of the second battery is less than the supply voltage of the first battery.

Example 19. System according to Example 18,
the supply voltage of the first battery being in the range from 20 V to 60 V,
the supply voltage of the second battery is in the range from 6 V to 18 V,

• Bereitstellen durch eine Gleichstromversorgung einer Versorgungsspannung zu einer elektrische Schaltung unter Verwenden einer ersten Masseklemme der elektrische Schaltung, und
• als Reaktion auf ein Masseverbindungsverlustereignis an der ersten Masseklemme, Laden aus der elektrische Schaltung eines Kondensators, der zwischen der ersten Masseklemme und einer zweiten Masseklemme gekoppelt ist.

Example 20. A method that includes:

• Providing a supply voltage to an electrical circuit by direct current supply using a first ground terminal of the electrical circuit, and
• in response to a ground connection loss event at the first ground terminal, charging from the electrical circuitry of a capacitor coupled between the first ground terminal and a second ground terminal.

• eine elektrische Schaltung,
• eine Hochspannungs-Gleichstromversorgungs-Masseklemme, die mit der elektrischen Schaltung gekoppelt ist,
• eine weitere Gleichstromversorgungs-Masseklemme, und
• einen Kondensator, der zwischen der Hochspannungs-Gleichstromversorgungs-Masseklemme und der weiteren Gleichstromversorgungs-Masseklemme gekoppelt ist.

Example 21. Device that includes:

• an electrical circuit,
• a high voltage DC power supply ground terminal coupled to the electrical circuit,
• another DC power supply ground terminal, and
• a capacitor coupled between the high voltage DC power ground terminal and the further DC power ground terminal.

Although the invention has been shown and described with reference to certain preferred embodiments, other persons skilled in the art may contemplate equivalents and changes in reading and understanding the specification. The present invention has all such equivalents and changes, and is only limited by the scope of the appended claims.

For the purposes of illustration, various scenarios were described above, in which a single capacitor is coupled between two ground terminals. Similar techniques can easily be applied to scenarios in which multiple capacitors, for example connected in parallel or in series, are coupled between two ground terminals.

Claims (21)

Device (100) comprising: an electrical circuit (110, 111, 112) configured to operate using a supply voltage of a DC power supply (171), a first ground terminal (101) coupled to the electrical circuit and associated with the DC power supply, a second ground terminal (102), and a capacitor (120) coupled between the first ground terminal and the second ground terminal. Device (100) after Claim 1 wherein the second ground terminal (102) is associated with another DC power supply (172) that is different from the DC power supply (171). Device (100) after Claim 1 or 2 wherein the device (100) is configured to charge the capacitor (120) from the electrical circuit upon a ground loss event at the first ground terminal. Device (100) after Claim 3 wherein the device (100) is configured to charge the capacitor (120) through another capacitor (215) of the electrical circuit. The device (100) of any preceding claim, further comprising: a monitor circuit (401) configured to monitor a voltage (489) across the capacitor. Device (100) after Claim 5 wherein the electrical circuit comprises an inverter (215, 216) for a motor / generator, the device (100) configured to control the motor / generator (220) by controlling the inverter (215, 216) in response to the monitoring turn off the voltage (489) on the capacitor. Device (100) after Claim 6 wherein the device (100) is configured to turn off switches (216) of the inverter if the voltage (489) across the capacitor exceeds a first threshold (481). The device (100) of any preceding claim, further comprising: a limiting circuit (450) configured to control a voltage (489) across the capacitor. Device (100) according to the Claims 7 and 8th wherein the limiting circuit (450) is configured to control the voltage (489) on the capacitor so that it remains below a second threshold (482) that is greater than the first threshold. Device (100) after Claim 8 or 9 wherein the limiting circuit (450) is configured to control the voltage (489) across the capacitor to remain above a third threshold (483). Device (100) according to one of the Claims 8 to 10 wherein the limiting circuit (450) is configured to form a low impedance bypass path of the capacitor (120). The device (100) according to any one of the preceding claims, wherein the electrical circuit comprises an inverter (214, 215, 216) for a motor / generator (220) and further comprises a transceiver (213) for a vehicle communication bus system (155, 156). Device (100) according to one of the preceding claims, wherein a capacitance of the capacitor is not less than 10 µF, optionally not less than 100 µF, further optionally not less than 1000 µF. The device (100) of any preceding claim, further comprising: a metal case that implements the second ground terminal. System (90) comprising: the device (100) according to one of the preceding claims, a first ground connection (161) of the direct current supply, which is coupled to the first ground terminal, a second ground terminal (162) of another DC power supply different from the DC power supply, the second ground terminal coupled to the second ground terminal, and a DC / DC converter (165) connected between the first ground terminal and the second ground terminal. System according to Claim 15 further comprising: another electrical circuit (155) configured to operate using the second supply voltage, wherein the electrical circuit and the further electrical circuit are coupled via a non-isolation interface (156). System according to Claim 15 or 16 , further comprising: a first battery (166) of the DC power supply, a second battery (167) of the further DC power supply, wherein a low-side terminal of the first battery is coupled to the first ground connection, and wherein a low-side terminal the second battery is coupled to the second ground connection. System according to Claim 17 , wherein a supply voltage of the second battery is less than the supply voltage of the first battery. System according to Claim 18 , the supply voltage of the first battery being in the range from 20 V to 60 V, the supply voltage of the second battery being in the range from 6 V to 18 V. A method comprising: Providing a supply voltage to an electrical circuit through a DC power supply using a first ground terminal of the electrical circuit, and in response to a ground connection loss event at the first ground terminal, charging from the electrical circuitry of a capacitor coupled between the first ground terminal and a second ground terminal. Device (100) comprising: an electrical circuit, a high voltage DC power supply ground terminal coupled to the electrical circuit, another DC power supply ground terminal, and a capacitor coupled between the high voltage DC power ground terminal and the further DC power ground terminal.

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